Steps to reproduce the issue

Looks like a normal behavior for any plugin, BUT the strings need to be loaded when the Action Logs - Latest module is displayed in backend (usually in CPanel)

Expected result

Actual result

Only solution I found was to add in joomla.ini the strings concerned:

; Common content type log messages
PLG_SYSTEM_ACTIONLOGS_CONTENT_ADDED="User <a href=\"{accountlink}\">{username}</a> added new {type} <a href=\"{itemlink}\">{title}</a>"
PLG_SYSTEM_ACTIONLOGS_CONTENT_ARCHIVED="User <a href=\"{accountlink}\">{username}</a> archived the {type} <a href=\"{itemlink}\">{title}</a>"
PLG_SYSTEM_ACTIONLOGS_CONTENT_DELETED="User <a href=\"{accountlink}\">{username}</a> deleted the {type} {title}"
PLG_SYSTEM_ACTIONLOGS_CONTENT_PUBLISHED="User <a href=\"{accountlink}\">{username}</a> published the {type} <a href=\"{itemlink}\">{title}</a>"
PLG_SYSTEM_ACTIONLOGS_CONTENT_TRASHED="User <a href=\"{accountlink}\">{username}</a> trashed the {type} <a href=\"{itemlink}\">{title}</a>"
PLG_SYSTEM_ACTIONLOGS_CONTENT_UNPUBLISHED="User <a href=\"{accountlink}\">{username}</a> unpublished the {type} <a href=\"{itemlink}\">{title}</a>"
PLG_SYSTEM_ACTIONLOGS_CONTENT_UPDATED="User <a href=\"{accountlink}\">{username}</a> updated the {type} <a href=\"{itemlink}\">{title}</a>"

Any better idea?